We have a great interest in pursuing methods to more effectively treat patients which coronary artery disease with symptoms refractory to conventional medical therapy, who are not candidates for coronary artery bypass surgery. A potential approach we investigated was implantation of the internal mammary artery (IMA) into an ischemic region of the left ventricle, to directly revascularize the myocardium independent of the coronary arteries. Long-term results of this procedure, pioneered by Vineberg in the 1940's and widely used before the advent of coronary artery bypass surgery, were controversial. The purpose of this investigation, completed in January, 1987, was to reassess with modern techniques the ability of this operation to provide nutritional flow to ischemic myocardium. Ameroid devices were applied to the left anterior descending coronary artery (LAD) in 23 dogs, effecting coronary occlusion over 2 to 3 weeks. In 14 dogs, the left was implanted in tramyocardially in the LAD zone. The IMA was not implanted in the remaining 9 dogs. After 8 weeks, microspheres were used to quantitate myocardial blood flow to the LAD zone and a control zone under basal conditions and during adenosine-induced vasodilatation, before and after IMA occlusion. Although IMA occlusion caused a detectable fall in LAD zone flow in half of the dogs, no changes in HR, BP, LIVEDP, or endo/epi flow rations were consistently observed. With the IMA patent, there was no difference in mean LAD zone flow between the two groups, either at rest or under conditions of maximal vasodilatation. Thus we concluded that implantation the IMA, while providing some degree of measurable myocardial blood flow in 50% of cases, was not an effective means of myocardial revascularization in this model.